Question

the diameter of roller is 84cm and its length is 120cm. it takes 500 complete revolution to move once over to level a playground. Find the area of playgroup

Answer 1

One revolution of roller = C.S.A of roller
= 2 pi r h
= 2 multiply 22/7 multiply 42
= 264cm^2
Total are of playground = 500 multiply Are of one revolution
= 500 multiply 264
= 132000 cm^2

Answer 2

given, diameter of roller=84 cm
length of roller= 120cm
no of revolution taken by the roller=500
radius= diameter/2= 84/2=42
in one revolution area covered by the roller= curved surface area of the cylinder =
$2\pi {r}h = 2 \times \frac{22}{7} \times 42 \times 120 \\ = 2 \times 22 \times 6 \times 120 = 31680 \: {cm}^{2}$
now area covered in 500 revolution
= 31680×500
=15840000 cm^2. or 1584m^2